1. Field
The present invention relates to a shaft drive type vehicle in which power of a power source is transmitted to an axle shaft through a drive shaft, a pinion gear, and a bevel gear.
2. Description of the Related Art
There is a shaft drive type vehicle in which power of an engine is transmitted to an axle shaft through a drive shaft, a pinion gear, and a bevel gear. In relation to this type of shaft drive vehicle, a configuration has been disclosed in which a pinion gear and a bevel gear are rotatably supported inside a final gear box, and these gears are lubricated with an oil contained in the final gear box (see, for example, Japanese Patent Laid-Open No. 2008-74286 (Patent Document 1)).
In Patent Document 1, a power transmission structure is described. In the power transmission structure, a third shaft portion is connected to a rear end portion of the drive shaft through a universal joint, and an outer cylinder portion is slidably connected to an outer circumferential surface of the third shaft portion through spline coupling. In addition, a third bevel gear is spline coupled to an inner circumferential surface of the outer cylinder portion, and the third bevel gear is meshed with an annular fourth bevel gear which converts a rotational axis by 90 degrees toward the direction of an axle. Further, a hub is fixed by press fitting to an inner circumferential portion of the fourth bevel gear. With such a structure, rotation of the drive shaft is transmitted to a driving wheel. In addition, Patent Document 1 describes a lubrication structure in which an oil hole piercing the outer cylinder portion in the radial direction is provided, and the location of splines present outside of the outer cylinder portion is lubricated through the function of the oil hole.
In the conventional configuration as above, however, the transmission structure between the drive shaft and the fourth bevel gear located on the most downstream side includes the third shaft portion, the outer cylinder portion splined coupled to the outer circumferential surface of the third shaft portion, and the third bevel gear spline coupled to the inner circumferential surface of the outer cylinder portion. Thus, the conventional configuration includes an increased number of component parts, which is disadvantageous for reduction in weight.
In addition, it is desired to supply a sufficient amount of an oil to the location of spline coupling, but mere provision of the oil hole in the outer cylinder portion may not be enough to achieve sufficient supply of the oil.